1. Field of the Invention
The present invention relates to an ink jet recording medium applied to a printer or plotter wherein an ink jet recording system is utilized.
2. Description of the Related Art
In recent years, the ink jet recording system can provide image quality comparable to that of photographs by virtue of the progress of a printing technology. For improving the image quality, the amount of ink in printing increases and the printing is also realized at high speed, and therefore the performance which ensures that ink is absorbed instantly and a large amount of ink is absorbed, is highly desired. At present, the recording medium is mainly a void-type recording medium that inorganic particles such as fine particle silica and alumina are used to form a layer having voids thereon and allows ink to be absorbed through the void. For improving the image quality, finer inorganic particles have been used. However, the finer the inorganic particles, the more sharply will the surface area thereof increase, and the surface activity thereof increases, and thus there is a problem that light resistance and yellowing resistance are remarkably deteriorated. Thus, it has been suggested that the organic particles are substituted for the inorganic particles.
Japanese Unexamined Patent Application Publication Nos. 2001-58461 and 8-216504 disclose that in the case where the cationic additives obtained by copolymerizing specific acrylic ester-based monomers are used without combining the inorganic particles therewith, provided is a recording medium which is excellent in water resistance and light fastness.
However, in these cationic additives, the organic particles form closest packing, thereby not providing sufficient voids, and thus there was a problem that satisfactory ink absorptivity is not obtained.
In order to prevent the closest packing, there has been proposed a method for coagulating the organic particles by a heat-sensitive gelling agent described in Japanese Unexamined Patent Application Publication Nos. 9-296067 and 9-296068. However, this method had a problem that it is difficult to control the aggregation thereof, a layer a layer having uniform voids is not formed, and thus ink absorptivity is partly varied, the particle size of the aggregate increases, and the color density is reduced.
On the other hand, Japanese Unexamined Patent Application Publication No. 6-227114 discloses the applications of the amphoteric polymeric organic particles having an anionic group and a cationic group as an ink jet recording sheet. Only use of ACCOSTAR C122 (manufactured by MITSUI CYANAMID, LTD.) of which the minimum film-forming temperature is 9° C. in Examples is exemplified, and the amphoteric ion latex is used as an adhesive of a pigment. In this technique, adhesiveness to the support, and surface strength and water resistance of the record sheet are improved, and further ink absorptivity is enhanced as compared to an aqueous emulsion-type polymer latex used as a conventional adhesive. However, the amphoteric ion latex is an emulsion having a high film-forming ability, which is used as an adhesive, and thus if a pigment is not combined therewith, ink absorption is not attained at all, thus the combination of the pigment being required. In addition, as a preferred example of the pigment, the fine particle silica is disclosed, which is used to, make up for the deteriorated, ink absorptivity, but light fastness and yellowing resistance cannot be prevented.
In addition, Japanese Examined Patent Application Publication No. 7-45526 discloses a method for preparing a cationic latex by copolymerizing cationic monomers, ethylenically unsaturated carboxylic acid monomers, aliphatic conjugated diene-based monomers and the other monomers, using a cationic emulsifying agent. In the technology described in the above publication, in the case where a latex essentially comprises aliphatic conjugated diene-based monomers and the latex is applied to an ink jet recording medium, light fastness of the latex is deteriorated due to the remaining double bonds derived from the aliphatic conjugated diene-based monomers, and thus there occurs a problem in a long term storage of the printed matter.
It is an object of the present invention to provide, for solving the above problems, an ink jet recording medium that is excellent in ink absorptivity, and also in color density, water resistance, light fastness and yellowing resistance.